In a typical solar cell, a p-n junction is formed on the light-receiving side of a semiconductor substrate such as a crystalline silicon substrate, and a light-receiving-side electrode for collecting photocarrier is firmed on the p-n junction. For improving the photocarrier collection efficiency of the entire light-receiving surface while suppressing shadowing loss, the light-receiving-side electrode of the solar cell is formed in a pattern shape. However, since there is a trade-off relationship between shadowing loss reduction and carrier collection efficiency improvement, enhancement of conversion efficiency by adjusting pattern shape of the light-receiving-side electrode is inherently limited.
In view of these situations, a back-contact solar cell has been proposed in which a p-type semiconductor region and a p-side electrode, and an n-type semiconductor region and an n-side electrode are disposed on the back side (a surface opposite to a light-receiving surface) of a semiconductor substrate. Back-contact solar cells have no electrode on the light-receiving side, and therefore the amount of light captured in a semiconductor substrate is increased, so that high conversion efficiency can be achieved.
In a back-contact solar cell it is necessary to pattern a semiconductor layer and an electrode so that leakage does not occur between a p-type semiconductor region and an n-type semiconductor region on the back side. In general, patterning is performed by forming a separation groove at a boundary portion between a p-type semiconductor region and an n-type semiconductor region. However, when the width of a separation groove is increased for reliably preventing leakage, the areas of a semiconductor region and an electrode that contribute to power generation are reduced, so that conversion characteristics cannot be sufficiently improved.
In view of such a problem, Patent Document 1 suggests forming a region (overlapping region) where a p-type layer and an n-type layer overlap each other. In the overlapping region, an insulating layer is disposed between the p-type layer and the n-type layer to prevent leakage between the p-type layer and the n-type layer. In the back-contact solar cell in Patent Document 1, the p-type layer and the n-type layer are separated from each other by the insulating layer disposed in the overlapping region, and an electrode separation groove is disposed near the center of the overlapping region to electrically separate the p-side electrode and the n-side electrode.